Effect of DC Superimposed AC Voltage on Partial Discharge Characteristics of LN2/PPLP Insulation System

This paper aims at studying the effect of DC superimposed AC voltage on partial discharge(PD) characteristics of LN2/PPLP insulation system for high temperature superconducting (HTS) cables. The pulse current method was adopted to measure the PD characteristics under the superimposed voltage with different DC components. The voltage virtual value (V rms ) of AC-DC superimposed voltage is set as 9 kV to analyze the effects of the DC component on the total process of partial discharge. The experimental results show that: under the composite voltage of positive DC and AC, the partial discharge characteristics of the internal butt-gap are affected by both the DC voltage and the AC voltage. The first occurrence of partial discharge is determined by the maximum peak value of the composite voltage. The number of discharges and the discharge amplitude decreases with the increases of DC component.